Neurons in a particular region of the brainstem, giant neurons just above the top of the spinal cord, are responsible for maintaining a fundamental function of the brain known as generalized brain arousal (GA). A lack of GA results in coma and death. Despite serving a crucial role, these neurons have not yet been isolated for study as cultured nerve cells. We have recently devised methods for isolating these neurons for cell culture using both mouse embryos and embryonic stem cells. We now propose to analyze the electrical properties of these cells for the first time, and to determine the gene expression patterns that make them unique. We will also design a system for testing the capacity of these cultured cells to function in the brain, by marking them with fluorescent proteins and re-introducing them into either mouse embryos or adult mice. Lastly, if the neurons are able to survive, we can test whether implanting them into brain-injured mice can reverse the problems with GA that these animals generally experience.